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2026 Iowa Electrical License Exam: Practice
Questions & Answers
1. What is the minimum size copper grounding electrode conductor for a 200-ampere service using a ground rod? A) 6 AWG B) 8 AWG C) 4 AWG D) 10 AWG Answer: A) 6 AWG Rationale: The NEC requires a minimum 6 AWG copper conductor for a single ground rod on a 200-amp service. 2. What is the maximum number of 20-ampere branch circuits that can be installed on a 100-ampere panel? A) 10 B) 12 C) 15 D) 20 Answer: C) 15 Rationale: Calculated using 80% of the panel capacity for continuous loads; 100 A × 0.8 ÷ 20 A ≈ 4, but the total number of circuits is based on panel rating and space. 3. Which type of conduit is suitable for wet locations? A) EMT B) PVC C) RMC D) All of the above Answer: D) All of the above
Rationale: EMT, PVC, and RMC are all rated for wet locations if installed according to code.
4. What is the NEC standard voltage for a dwelling branch circuit? A) 120/208 V B) 120/240 V C) 240/480 V D) 277/480 V Answer: B) 120/240 V Rationale: Standard residential branch circuits are 120/240 V single- phase. 5. A receptacle in a bathroom must be GFCI protected if it is within: A) 3 feet of the sink B) 6 feet of the sink C) 2 feet of the sink D) 5 feet of the sink Answer: B) 6 feet of the sink Rationale: NEC requires GFCI protection for all receptacles within 6 feet of a bathroom sink. 6. What is the maximum allowable voltage drop for branch circuits in a dwelling? A) 2% B) 3% C) 5% D) 10% Answer: B) 3% Rationale: NEC recommends a maximum 3% voltage drop for branch circuits to maintain efficient operation.
10. Which type of conductor insulation is suitable for 90°C in wet locations? A) THHN B) THWN C) TW D) UF Answer: B) THWN Rationale: THWN is rated for 90°C in wet locations. 11. What is the correct color for a grounded conductor in residential wiring? A) Black B) White C) Green D) Red Answer: B) White Rationale: NEC identifies white or gray as the color for grounded (neutral) conductors. 12. Which device provides protection against overcurrent? A) GFCI B) AFCI C) Circuit breaker D) Outlet Answer: C) Circuit breaker Rationale: Circuit breakers interrupt current flow when overload or short-circuit occurs.
13. What is the minimum height for a service disconnect from the finished floor? A) 4 ft B) 5 ft C) 6 ft D) 7 ft Answer: B) 5 ft Rationale: NEC requires the service disconnect to be accessible and typically within 6.5 ft from the floor. 14. What is the minimum burial depth for a 120 V, 20 A PVC conduit in a residential yard? A) 12 inches B) 18 inches C) 24 inches D) 30 inches Answer: B) 18 inches Rationale: NEC Table 300.5 specifies 18 inches for PVC conduit under residential areas. 15. How is a multiwire branch circuit identified? A) By color-coded conductors B) By labeling C) Both A and B D) None Answer: C) Both A and B Rationale: Multiwire branch circuits must be color-coded and labeled to indicate the shared neutral.
A) 2 ft B) 4 ft C) 6 ft D) 8 ft Answer: B) 4 ft Rationale: NEC limits flexible cord lengths to maintain safety and avoid damage.
20. What is the minimum ampacity for a feeder supplying a 60- ampere load? A) 6 AWG B) 8 AWG C) 4 AWG D) 10 AWG Answer: C) 4 AWG Rationale: NEC Table 310.16 shows 4 AWG copper supports 70 A, which safely covers 60 A. 21. What is the standard spacing for smoke detectors in a dwelling? A) Every 10 feet B) Every 12 feet C) Every 15 feet D) Every 20 feet Answer: B) Every 12 feet Rationale: NEC and NFPA 72 recommend smoke detectors be spaced no more than 12 feet apart. 22. What is the maximum number of current-carrying conductors in a 2-inch EMT conduit before derating? A) 4
B) 6
C) 8
D) 9
Answer: D) 9 Rationale: NEC Chapter 9, Table 310.15(B)(3)(a), requires derating when more than 3 current-carrying conductors are in a conduit.
23. A lighting branch circuit with 15 A breaker can have a maximum load of: A) 1200 W B) 1440 W C) 1800 W D) 1500 W Answer: B) 1440 W Rationale: 120 V × 15 A × 0.8 (continuous load) = 1440 W. 24. Which type of grounding is required for a metal water pipe? A) Supplementary B) Equipment C) Main D) Isolated Answer: C) Main Rationale: NEC requires metal water pipes in contact with earth to be grounded to the main grounding electrode system. 25. Which conductor is typically red in a 120/240 V three-phase system? A) Neutral B) Grounded C) Phase B
Rationale: NEC 110.26 specifies 36-inch-wide working space in front of equipment.
29. Which type of breaker is required in a damp basement for a 120 V circuit? A) Standard B) GFCI C) AFCI D) None Answer: B) GFCI Rationale: NEC requires GFCI protection in damp or wet locations like basements. 30. A motor rated at 20 A requires a minimum feeder breaker of: A) 20 A B) 25 A C) 30 A D) 40 A Answer: C) 30 A Rationale: NEC 430.52 requires 125% of the motor full-load current for sizing branch-circuit protection. 31. What type of wire is required for a 100-amp residential service entrance cable? A) 2 AWG aluminum B) 1 AWG copper C) 1/0 AWG aluminum D) 3/0 copper Answer: C) 1/0 AWG aluminum
Rationale: NEC Table 310.16 specifies 1/0 aluminum for 100-amp service.
32. What is the NEC required minimum size for a grounding electrode conductor to a concrete-encased electrode? A) 4 AWG B) 6 AWG C) 8 AWG D) 10 AWG Answer: A) 4 AWG Rationale: NEC 250.66 specifies 4 AWG copper minimum for a concrete-encased electrode. 33. What is the maximum distance a 15 A receptacle can be from a sink in a kitchen? A) 2 ft B) 3 ft C) 4 ft D) 6 ft Answer: D) 6 ft Rationale: NEC requires GFCI protection within 6 feet of sinks. 34. Which conduit type is prohibited in underground residential locations without concrete encasement? A) PVC Schedule 40 B) RMC C) EMT D) None Answer: C) EMT
38. The maximum spacing for outdoor receptacles along a dwelling’s exterior wall is: A) 6 feet B) 10 feet C) 12 feet D) 15 feet Answer: C) 12 feet Rationale: NEC requires outdoor receptacles spaced no more than 12 feet apart. 39. What is the purpose of a neutral in a single-phase 120/240 V system? A) Carry unbalanced current B) Provide a return path for current C) Stabilize voltage D) All of the above Answer: D) All of the above Rationale: Neutral provides return path, stabilizes voltage, and carries unbalanced current. 40. How is a grounding conductor identified? A) White insulation B) Green or bare C) Black or red D) Blue or yellow Answer: B) Green or bare Rationale: NEC identifies grounding conductors as green or bare copper.
41. What is the minimum ampacity for a branch circuit supplying a 40 A air conditioner? A) 40 A B) 45 A C) 50 A D) 60 A Answer: C) 50 A Rationale: NEC requires 125% of full-load current for continuous loads. 42. A 4 AWG aluminum feeder is rated for how many amperes? A) 50 A B) 55 A C) 65 A D) 70 A Answer: D) 70 A Rationale: NEC Table 310.16 shows 4 AWG aluminum for 75°C terminals is 65–70 A. 43. Which conductor is used for grounding metal boxes? A) Neutral B) Grounding conductor C) Hot conductor D) None Answer: B) Grounding conductor Rationale: Metal boxes must be grounded to prevent shock hazards. 44. What is the minimum size of copper service entrance conductors for a 60-ampere service? A) 6 AWG
D) Both A and B Answer: B) GFCI Rationale: NEC mandates GFCI protection for all countertop receptacles.
48. Maximum continuous load on a 15-amp branch circuit? A) 12 A B) 15 A C) 10 A D) 8 A Answer: A) 12 A Rationale: 80% of 15 A = 12 A for continuous loads. 49. Which device protects against arc faults? A) GFCI B) AFCI C) Standard breaker D) Fuse Answer: B) AFCI Rationale: AFCI breakers detect arcing and prevent fires. 50. What is the minimum size copper conductor for a 100-amp service to a dwelling? A) 2 AWG B) 4 AWG C) 1 AWG D) 6 AWG Answer: B) 4 AWG Rationale: NEC Table 310.16 indicates 4 AWG copper is suitable for 100 A residential service.
51. What is the maximum distance a bathroom receptacle can be from the edge of a bathtub or shower stall? A) 2 feet B) 3 feet C) 6 feet D) 8 feet Answer: C) 6 feet Rationale: NEC requires GFCI protection within 6 feet of any tub or shower to prevent shock hazards. 52. A 3-phase, 480 V feeder has a load of 90 A. What size copper conductor is required? A) 1/0 AWG B) 2/0 AWG C) 3/0 AWG D) 4/0 AWG Answer: B) 2/0 AWG Rationale: NEC Table 310.16 specifies 2/0 AWG copper at 75°C terminals can safely carry ~100 A for a 480 V 3-phase feeder. 53. Which type of conductor is required to connect a metal water pipe to the grounding electrode system? A) Aluminum B) Copper C) Steel D) Any conductor Answer: B) Copper Rationale: NEC 250.66 requires copper for reliable corrosion-resistant grounding.
57. Maximum allowable voltage drop for feeders supplying critical loads? A) 2% B) 3% C) 5% D) 10% Answer: A) 2% Rationale: NEC recommends 2% for feeders to maintain voltage quality for sensitive equipment. 58. Which type of wiring method is permitted inside a concrete slab? A) NM cable B) UF cable C) MC cable D) EMT conduit Answer: D) EMT conduit Rationale: NEC allows rigid metal conduit for wiring inside concrete slabs; NM and UF cannot be embedded in concrete. 59. What is the minimum number of 20 A circuits required for a laundry area? A) 1 B) 2 C) 3 D) 4 Answer: A) 1 Rationale: NEC requires at least one 20 A branch circuit dedicated to laundry receptacles.
60. Which conductor is used for bonding metal raceways? A) Grounded conductor B) Grounding conductor C) Ungrounded conductor D) Neutral Answer: B) Grounding conductor Rationale: Grounding conductors bond metal raceways to ensure fault currents have a low-resistance path. 61. What is the maximum height for wall receptacles in a residential bathroom? A) 36 inches B) 42 inches C) 48 inches D) 54 inches Answer: C) 48 inches Rationale: NEC does not specify exact height, but 48 inches maximum keeps receptacles accessible while safe from splashes. 62. Minimum burial depth for direct-buried UF cable under a driveway? A) 12 inches B) 18 inches C) 24 inches D) 30 inches Answer: C) 24 inches Rationale: NEC Table 300.5 specifies 24 inches for direct-buried UF cable under driveways or vehicular traffic.
